How Does a Fireplace Blower Work?

Should you consider adding a blower to your gas or wood fireplace?

A fireplace can make a beautiful addition to your home, whether you enjoy the romantic dance of flames or the warm feeling of a fire on a cold night, there are literally hundreds of models and variations to choose from. While everyone's reason for choosing a fireplace is different, many of us purchase fireplaces for their ability to be used as heating appliances. While it's true that gas fireplace efficiency has improved over the years, gas fireplaces still exhibit some degree of heat and energy loss.  Unfortunately, no fireplace is truly 100% efficient.  Heat is not only lost through the venting process, but radiant heat alone is not without parasitic heat transfer loss.  The type of gas fireplace you have also plays an important role in the overall efficiency and heating capability of your fireplace.  To combat the inefficiencies of radiant heat and to lessen heat loss through venting, adding a blower or fan kit can significantly improve the overall efficiency of your fireplace.  In fact, some blowers can improve gas fireplace efficiency by as much as 80%!

But what about wood fireplaces?  As is the case with gas fireplaces, there are several choices to consider when choosing a wood fireplace. Maybe you have a natural stone fireplace and chimney, or maybe you're looking to add a wood insert or stove.  Like their gas counterparts, many wood burning fireplaces offer an option to add a blower.  Some wood fireplaces even have separate blowers for combustion and convection.  And while the thermodynamics of wood burning fireplaces are the same, their efficiency and heating attributes can vary widely.  Adding a blower to a wood fireplace, insert or stove is an extremely effective way of improving both the efficiency and comfort of a wood fireplace.  We'll talk more below on how to choose the correct blower kit for your gas or wood fireplace.

So what are the benefits of adding a blower?

Winter is ALWAYS around the corner, and if you're like me, the thought of another seemingly never ending season of cold weather, snow drifts, and iced locks seems unbearable. This doesn't mean; however, that your time spent indoors must be spent in the cold.

Fireplaces are becoming an increasingly popular appliance installed in just about every new home and condo. Chances are you already have a fireplace installed, but rarely use it for fear of its operating expense. But when compared to running a standard home furnace, fireplaces can be a wonderful alternative source of heat.  Used in conjunction with your home's primary source of heat, a fireplace equipped with a blower or fan kit can help save you hundreds of dollars annually in wasted energy. Adding a blower kit can literally pay for itself!

Some benefits:

How does a fireplace blower work?

The answer to this question varies depending on the type of fireplace we're discussing. 

In a gas or wood insert, the blower is most commonly placed below the insert.  On a gas fireplace, the blower is usually positioned against the rear wall facing upwards, although it's not uncommon to see blowers positioned on either side of the fireplace.  The blower draws in cool room air and forces that air upwards along the back or side of the fireplace.  The air is heated as it travels upwards, ultimately exiting the the top of the fireplace as warm air.  The same principle is true on wood inserts; however, the blower is usually placed towards the front rather than at the rear.  Ambient temperatures below a wood burning insert are much hotter than their gas counterparts, so the blowers are positioned closer to the front for cooling.  Rather than forcing air upwards, wood insert blowers force the air towards the rear wall.  Not exactly the most aerodynamic design, given that fireplace manufacturers love right angles, but blower positioning on a wood insert has more to do with prolonging the blower's life than it does the efficient flow of air. 

So what about free-standing stoves like legged and pedestal models that sit in the middle of your room?  In an enclosed insert, volume and pressure play a role in how blowers effectively move air.  However, a blower installed on free-standing stove is designed more for distribution than it is circulation around an enclosure.  Adding a blower to a free-standing stove is a great way of distributing heat faster and more efficiently than if you weren't using one at all.  Just as ceiling fans help distribute air evenly, so to do stove blowers, so their roles are similar.

Gas and wood fireplace types

Before we continue, let's talk briefly about the different types of gas and wood fireplaces, since they're mentioned rather frequently here.

Gas fireplaces typically come in one of four different types.  Vent-free, power vent, B-vent (natural vent) or direct-vent.  Each has their pros and cons, so it's important to consider which is right for your specific application. We won't get into the specifics of each here, but what's important to note is that efficiency ratings and heat output can differ between the various types.  So if you're considering a gas fireplace, it's important to discuss your options with a qualified expert, who can walk you through the pros, cons and features of each type.

The same goes for wood burning fireplaces. The most common types are masonry fireplaces, wood inserts, wood stoves, and wood fireplaces.  There are even alternative fuel fireplaces that burn everything from wood pellets to corn.  Again, the efficiency and purpose of each wood burning type is important to consider if you're purchasing new, so always discuss options with a qualified expert in your area.

Will my fireplace accept a blower kit?

The most widely asked question we receive is, "what blower kit does my fireplace use?".  First, it's important to determine if your fireplace will even accept a blower. Not all fireplaces do unfortunately.  As a general rule of thumb, gas fireplaces that allow for the addition of a blower or fan kit are considered circulating style units. Circulating style fireplaces typically have upper and lower panels that are either vented, non-sealed or louvered.  Louvered panels, for example, allow air to flow into the lower section of the fireplace and out through the top of the fireplace.  Fireplaces that have solid, flat or sealed panels are often considered non-circulating.  This rule may or may not apply evenly to certain types of wood burning fireplaces.  Wood fireplaces and wood inserts that accept blowers generally must also be circulating style units, but that isn't always a hard rule on some free-standing stoves.  On legged stoves, for example, the blower is often installed below or behind the stove.  The blower in this case merely helps distribute radiant heat vs improving the convection process of a circulating style fireplace. 

So what if you have a non-circulating fireplace?  Are you out of luck?  Not always.  Some manufacturers provide options on panel design, so if you have solid non-circulating panels for example, you can check with your manufacturer and see if they provide louvered replacement panels. 

The easiest way to determine if your fireplace accepts a blower or fan kit is to consult your owner's manual.  The owner's manual will almost always indicate the correct blower for your model of fireplace.  You can also use our Find My Blower tool located on several of our pages.  We've accumulated data on dozens of fireplace manufacturers and thousands of fireplace models.  If you can't find your fireplace manufacturer or model listed in our tool, please don't hesitate to contact us directly with any questions.  An expert will be more than happy to help you.

Which blower kit should I use?

Your fireplace's manufacturer typically makes recommendations on which blower or fan kit to use based on your fireplace's model number. FireplaceBlowersOnline.com offers a wide range of aftermarket blower kits that exceed OEM specifications. Our website provides an easy way to search, locate and purchase the right blower kit for your specific fireplace. If the correct blower kit for your fireplace has either been discontinued or is no longer available, we can often times recommend a universal blower kit.

How long do blowers last and how should they be maintained?

The lifespan of a blower in our experience is predicated on three things.  First, quality of the blower matters!  We discuss bearings in more detail below, but there's more than just bearings that go into a blower. The quality of shaded-pole motor used, the motor's insulation rating, shaft size, RPM rating, energy consumption, air flow characteristics, size and balance of wheel and proper bench testing all matter.  Second, environment plays a significant role in the longevity of a blower motor assembly.  Will the blower be operating in a clean and dust free environment?  Or will the blower be used in a high heat environment?  These are just some of the environmental concerns we have when answering this question, but limiting exposure to foreign contaminants and lowering the blower's exposure to overheating are things to certainly consider.  And lastly, how well is the blower being maintained?  Sleeve or bushing bearings must be periodically lubricated to prevent material wear, while sealed ball bearing blowers typically require no bearing maintenance.  However, all blowers should be periodically removed from the fireplace and thoroughly cleaned.  Fireplaces are not exactly clean environments.  A blower will draw in dust and debris, which will accumulate on the surfaces of the motor and wheel.  It will also penetrate non-sealed bearings.  The debris can effect the weight and balance of the blower wheel and cause premature motor and bearing wear.  Foreign contaminants can also slow moving parts and decrease their lifespan.  A thorough cleaning is suggested several times a year.   We like cleaning the blower before shutting down the fireplace for the warm seasons and we like cleaning the blower at least once a month during the operational seasons.  In some cases, we'll even suggest cleaning the blower more often, especially in high heat wood burning applications where ash penetration and foreign contamination is more prevalent.

What blower kit options are available?

Fireplace fan kits come in many forms and can often times include several different accessory options.  Your owner's manual will typically recommend a specific blower kit option for your make and model fireplace.  A blower kit will include everything you need for installation, with the exception of basic tools.  Kits include the blower, power cord, mounting hardware (if required), wiring harness and required controllers. These controls can include thermostats, rheostats, remote controls and fireplace specific modules.  Our aftermarket kits all come pre-assembled and pre-wired for easy installation, while the OEM kits we offer will vary in difficulty based on the manufacturer and type of kit.

It's also important to note that accessories can either be required or optional.  Let's say for example that your home installation uses a single wall switch to control turning the fireplace on and off.  Your fireplace will also have an electrical outlet below it that is used for the blower.  Since the blower's electrical outlet isn't controlled via the wall switch, we'll need a way of controlling how and when the blower is turned on and off.  We can accomplish this one of two ways - or both.  First, we can use a variable speed controller, which has its own on and off position.  Secondly, we can use a thermostat / temperature sensor, which measures the surface temperature of your fireplace and determines when to turn the blower on and off automatically.  We can also use both!  Let's talk about each of these controllers in more detail below and clarify when they are either optional or required.

Rheostats & Variable Speed Controllers

So what exactly is a rheostat?  A rheostat is a resister that controls the amount of current through a circuit.  We use rheostats as a method for controlling the RPM speed of the blower's motor. By controlling the speed at which the blower operates, you can control both air flow and noise. A blower running at it's highest RPM speed produces more air flow, while a blower running at a lower RPM speed produces less air flow. Noise is also a factor to consider. While a fast running blower produces more air flow, it also tends to produce more noise. And visa versa. In blower kit applications, there are typically two types of variable speed controls used. Some kits use an inline variable speed control that is connected into the wiring harness of the blower. These variable speed controls are typically installed below the fireplace. Some fireplaces provide specific mounting locations for these types of variable speed controls. The second type of variable speed control used is the wall mounted control. These rheostats are commonly used to replace wall switches that control the blower's electrical outlet.  They work the same as the inline rheostats, but provide a more convenient location for controlling the blower.  Please note that a dedicated wall switch for the blower is required before a wall mounted rheostat can be used. 

The rheostats we use in our kits include an ON/OFF position and allow you to control the full RPM range of the blower. Light dimmers and ceiling fan switches can be used, but they must be rated properly for use in a blower kit application. Therefore, we recommend dimmers be in the 3-5 amp range. Failure to use a properly rated dimmer will result in improper blower control, audible feedback from the blower, and possible damage to the blower's motor.

Thermostats

A thermostat limit switch, also referred to as a temperature sensor, is most commonly used in blower kit applications when there is no designated wall switch installed for the blower. When a fireplace is installed, manufacturers provide options as to how the fireplace is configured and wired.  Some installations have a single wall switch, while others have two or even three.  When no wall switch has been installed for the blower, a thermostat switch makes it possible to control the blower's on and off operation automatically.  Thermostats can also be used in applications where a designated wall switch HAS been installed for the blower.  In these installations, the wall switch is left in "ON" position so that power is always being supplied to the outlet. The thermostat in this case takes control of determining when the blower is turned "ON" and "OFF".

So how does a thermostat limit switch work? Thermostat limit switches work by opening and closing a circuit at predetermined temperatures. In most fireplace blower kit applications, these temperatures are 90°F and 120°F. The switch closes at 120°F (blower on) and opens at 90°F (blower off). Through repeated testing, we have found that limit switches with an operating temperature range of 90°F / 120°F, function best for most gas fireplace applications. Some of our wood burning thermostats, depending on the application, operate in a different range because of temperature variances between gas and wood fireplaces.  Thermostats are installed a few different ways.  In most cases, they are wired inline with the blower's wiring harness and attached to the underside of your fireplace via a magnetic bracket.  Some are considered "snap" style thermostats and have clips that hold them flush to the surface of the fireplace.  Others vary based on the fireplace, blower kit application and manufacturer recommended location of the sensor.

Timers

A timer is exactly as it sounds.  Rather than a thermostat automatically controlling when the blower turns on and off, a timer allows you to determine when the blower turns on and off based on a given increment of time.  Basic timers have preset durations and are wired directly into the blower's wiring harness.  They are often included as part of the blower kit.  More complicated and programmable timers are integrated into remote controls, which are purchased separately from the blower kit and require some additional installation steps.

Remote Controls

Remote controls help extend your reach and offer some cool features that aren't always included with a standard fireplace blower kit.  Remote controls vary widely in their design, complexity and control, but offer users an easy way of controlling their fireplace from the comfort of their favorite chair.  It's not uncommon for fireplace manufacturers to provide the option or include an integrated remote control with their fireplaces.  Some remote controls can control everything from on/off operation to flame height and blower speed.  Simpler options control fireplace on/off operation only, while others include timer features.  When choosing a remote control, you'll need to consider your fireplace, your application and the features you're looking for a remote control to operate.  If your manufacturer doesn't offer a remote control option for your model, there are excellent aftermarket solutions from manufacturers like Skytech and others to consider. 

High Temperature Wiring

In the previous section, we discussed thermostat limit switches and how they're used in fan kit applications. While most of these limit switches are mounted underneath the firebox using a magnetic bracket, some thermostats must be mounted in a manner that requires the use of high temperature rated wire. This wire is included with all of our fan kits that require high temperature rated wire.  You can also request this type of wire for custom installations

Home Automation

While the fireplace industry has been somewhat slow to adopt newer technologies, home automation is finally starting to gain traction.  Smart switches, relays, and apps will soon replace legacy modules, timers and remote controls.  The question becomes whether manufacturers take a proprietary approach, think Apple, or whether manufacturers will consider open source platforms that allow engineers and developers to design and develop customized features and controls.  We're hoping the later is true, since open source would allow engineers and app developers to create non-manufacturer specific technology.  Additionally, many of the home automation platforms currently available are open source to some degree.  The demand for Alexa and Google Home voice control, along with compatibility to popular home automation hubs like Hubitat and SmartThings, are steadily increasing.  So it will certainly be interesting to see what side of the isle manufacturers fall. 

Ball vs. Sleeve Bearings.  Which is Better and Why it Matters.

There has been an ongoing debate over the type of bearings used in fireplace blower applications, so let's discuss the two most popular options and why we've chosen one over the other.  A standard single blower motor assembly has 3 bearings. Two for the motor (inside and outside) and a single outboard or wheel bearing used at the end of the assembly for the blower's wheel.  The two most widely used bearing types used in blower assemblies are sleeve, sometimes referred to as bushings, and ball bearings.  While there are pros and cons to each, we'll focus our discussion around their application with blowers vs a general discussion on the two bearing types.

Sleeve Bearing Blowers

Sleeve or bushing bearings are the most common bearing type found in shaded-pole induction motors and therefore fireplace blower assemblies.  They are often made of bronze or brass.  While bronze is technically a better material choice for sleeve bearings, due to it's harder material strength, both require an external lubricant and both can exhibit deformation and premature wear.  Because of their cheaper material and production costs, sleeve bearings tend to be a less expensive option than than their ball bearing counterparts.  And while they have a tendency to operate quietly during their initial lifespan, sleeve bearings have a tendency to degrade faster with continual use, as they are prone to the effects of friction under high RPM loads. Additionally, bushings are more prone to the effects of foreign contaminates and heat, which can impact their performance and lower their operating lifespan.

Pros:

• Quiet early life
• Inexpensive

Cons:

• Become noisier with bearing fatigue
• Requires maintenance (lubrication)
• Bearing lifespan

Ball Bearing Blowers

The alternative to sleeve bearings is ball bearings. Fireplace blower applications use a sealed ball bearing design.  A sealed bearing prevents contaminant intrusion and ensures the correct amount of lubricant is supplied to the bearing.  Additionally, sealed ball bearings require zero maintenance and can be designed purposely for the environment they'll be operated in.  Because of these features, we're able to select bearing tolerances based on size, RPM speed, heat and lubrication type. Despite these obvious advantages, noise and lifespan must still be taken into account.  Ball bearings used to be louder than their sleeve bearing counterparts, but technological advances in their design have all but eliminated some of the earlier concerns over using ball bearing assemblies.  We use very high quality Japanese sealed bearings in the motor and on the outboard side of the blower housing. By exclusively using ball bearings in all of our aftermarket blowers, we've improved lifespan, heat tolerances and lowered general maintenance concerns.  Additionally, our bearings have much tighter tolerances, so we get perfectly balanced and smooth rotating wheels as a result. And we've done this without having to sacrifice a quiet running blower assembly.

Pros:

• No maintenance
  
• Quiet
• Heat tolerant
• Prevents outside contamination
• Prevents over lubrication
• More balanced

Cons:

•  More expensive
  

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